1. Field of the Invention
The present invention relates to a flexible, electrically insulating pipe connection between the water distribution chamber and the end of the coil top on the side of the distribution chamber on a water-cooled rotor of an electrical machine. A pipe connection of this kind is known, for example, from Swiss Pat. No. 577,135.
2. Description of the Prior Art
Pipe connections between water distribution chambers and the winding leads in the coil end of a water-cooled rotor of an electrical machine determine the operating safety of the electrical machine. In order to meet the requirements demanded of them, the pipe connections must have the characteristics of electrical potential separation between the water distribution chamber (at ground potential) and the winding potential, and compensation for thermally and mechanically caused relative movements between the coil end and the water distribution chamber, which is rigidly connected with the body of the rotor.
The known pipe connections which have these characteristics can essentially be divided into two categories. In the first category, for example according to the Swiss Pat. No. 577,135, the pipe connection consists of a hose section formed of plastic with two connecting pieces of metal which project with a nipple into the hose at the ends of the hose and which are connected with the base section by means of a sleeve-shaped fastening component resting against the outer circumference of the hose. The hose section is provided with a compression-resistant shielding which extends to below the two fastening components. At least one end of the hose section projects beyond the sleeve-shaped fastening component. Thus, the required characteristics of thermal separation and relative movement compensation are incorporated in a single structural component, the plastic hose.
In the second category of pipe connections, as it is described and shown in Swiss Pat. No. 595,715 for example, metal pipes are connected to the water distribution chamber with insulating connecting links in between for the electrical potential separation. The metal pipes run mostly in grooves in the rotor shaft at the coil end on the side of the rotor ball. Flange-shaped and ring-shaped supports are provided in the space outside the coil end while the radial fastening of the metal pipes is effected below the coil end by means of grooved wedges. Relative movements between the coil end and the insulating connecting links, which are rigidly connected with the rotor shaft, are absorbed by the flexibility of the metal pipes.